HEAVY METALS POLLUTION IN MUSCLE, CRAW, KIDNEY,
LIVER AND PLANT FOOD GIVEN TO CHICKENS
IN THE AREA AROUND PROBISHTIP
Full professor Snezana Stavreva Veselinovska
“Goce Delcev” University, Stip, R, Macedonia
ABSTRACT
Permanent intake of residues through meat, even if only of one of them and in small
quantities, can over time cause the appearance of new chemical compounds that can
cause chronic disease in humans due to cumulation and synergic action. Symptoms
usually appear even when it is too late to intervene. The issue here is the fact that in
this case there is no so-called alarm signal which is characteristic of infections caused
by microorganisms and which would make a person feeling it seek help from a
doctor. The increasingly more frequent fatigue attributed to hard work, a growing
number of anxious people because of a deadly pace of life, headaches the occurrence
of which is explained in different ways, heart pain etc., are probably consequences of
the new nutritional era, i, e, of the effect of biological debris introduced into the
human organism through meat and other products.
Toxic metals get into meat through contaminated cattle feed, and partly through
contaminated water or air. Of toxic metals which can be found in meat selenium
should be mentioned first because it is often given to animals as prevention from
certain phenomena that negatively affect the quality of the meat. As samples for
proving the presence of selenium in meat, fat (the amount should be less than
1mg/kg) and muscle tissue is taken, as well as liver and kidney. It should be noted
that during the inspection of meat, the largest amounts of toxic trace elements can be
found in the kidney, then liver and in other organs.
The paper will show the results for the content of lead, cadmium, arsenic and
mercury in 11 different samples of muscle, craw, kidney, liver and plant food given
to poultry (chickens) in the area around Probishtip.
Key words: heavy metals, pollution, lead, cadmium, arsenic, mercury, muscle, craw,
kidney, liver, plant food, chickens, coefficients of correlation
Introduction
Lead is a toxic metal that can be found everywhere in the environment.
Overexposure to lead continues to be an important worldwide problem. Food is an
important source of lead and determination of lead in food can be used for the
estimation of lead exposure. The level of lead in the Earth’s crust is about 20 μg/g.
The Industrial Revolution gave rise to an increase in the amount of lead in the
environment and an even bigger increase occurred around 1920 when leaded gasoline
was introduced. Leaded gasoline is still not banned everywhere in the World, and it
still used in the developed countries. In areas where leaded gasoline is banned, the
major exposure pathways of nonsmoking adults are from food and water. Several
studies were done to determine the concentration of lead in foods [10, 14] and to
study its dangerous effects. Recently, the USA, all European countries and many
developing countries have outlawed or strictly regulated the use of leaded petrol. In
such countries, levels of lead in food and drinking water are closely monitored. Lead
may reach and contaminate plants, vegetables, fruits and canned food through air,
water and soil during cultivation and also during industrial processing and packaging.
Fruits and vegetables grown in polluted soils may become contaminated as a result of
plant uptake of lead from soils or direct deposition of leaded dust onto plant surfaces.
Therefore, through these diverse mechanisms, lead deposited in soil becomes a
persistent and long-term source of lead exposure for humans.
Lead exposure can occur through food, water, soil, air and the relative
contributions from individual sources may depend on lifestyle and socioeconomic
status. It was reported that the main sources of exposure for an adult are food
(ranging from 0.4 μg/kg bw/week to 10.1 μg/kg bw/week) and water (ranging from
0.23 μg/kg bw/week to 0.35 μg/kg bw/week). The main potential sources of exposure
to lead in children are food, air, water and dust or soil.
Watanabe et al. [26] reported that people, especially those who consume rice
as a staple food for daily energy, are inevitably exposed to significant amount of lead
via rice. Rice crops, even from non polluted areas, may be contaminated because of
fertilizers that are used in forms containing lead. Amongst other foods fish are
constantly exposed to lead from polluted water. Lead accumulates in their bodies
tissues in different amounts depending on the size and age of fish [23, 24]. Canned
fish, especially canned tuna fish, is abundantly consumed because of its convenient
and affordable use. In the same respect, several studies [17-19] have reported that the
lead content in different type of chocolates varied between 0.07 and 4.0 μg/g product.
The United Nations World Health Organization (WHO) has also given
recommendations for maximum lead content in food and water [3, 27]. The Joint
FAO/WHO Expert Committee on Food Additives (JECFA) [28] has established a
provisional tolerable weekly intake (PTWI) of 25 μg/kg bw/ week for lead. PTWI is
an estimate of the amount of a contaminant that can be ingested over a lifetime
without appreciable risk. An intake above the PTWI does not automatically mean that
health is at risk. Transient excursion above the PTWI would have no health
consequences provided that the average intake over long period is not exceeded as the
emphasis of PTWI is a lifetime exposure. Developing countries have been slow in
putting in place regulatory restrictions on leaded products, and leaded petrol is still
used in some cases. There is very little data on the magnitude of the contamination
levels of lead in environment and in food in these countries. Lead can be very
harmful even at low concentrations when ingested over a long time. After ingestion,
the absorption rate of lead ranges from 3% to 80%, whereas the typical absorption
rates of dietary lead in adults and infants are 10% and 50%, respectively. After
absorption, lead is initially distributed to soft tissues throughout the body via blood,
and then deposited in bone. Lead is excreted through the kidney and to a lesser extent
in the bile while non-absorbed dietary lead is excreted in the feces. Organic lead may
be metabolized to inorganic lead. The concentration of lead in blood is commonly
used as a biomarker of exposure. Lead is a classical chronic toxic chemical. It may
cause damages to kidneys, the cardiovascular, immune, hematopoietic, central
nervous and reproductive systems. Short term exposure to high level of lead can
cause gastrointestinal distress, anemia, encephalopathy and death. The effect of
exposure to lead varies according to dose and the age of the exposed person.
Manifestations of lead poisoning are nonspecific abdominal pain, constipation,
irritability, malign, muscle aches, headache, anorexia, and decreased lipid
concentrations. The Kingdom of Saudi Arabia (KSA) imports a lot of foodstuffs from
several countries. These foods may be subjected to lead contamination as described
above. The objective of this work was to estimate the levels of lead that may be
present in some foods available in local markets in Riyadh city, to determine the food
daily intake from the Food Consumption Survey (questionnaire) conducted in local
population in Riyadh city 2010, and consequently the daily lead intake from food
(questionnaire) and finally, to compare lead intake from the questionnaire with that
from the food balance sheet of the KSA provided by the FAO.
Lead is ubiquitous in the environment, persists indefinitely, and can be found
at low levels in almost all living organisms [5]. Sources of lead contamination of air,
water, and soil include internal combustion engines, oil burners, smelters, lead pipes,
glass and alloy processing plants, incinerators, industrial effluents, and smokestack
fallout [11]. Lead is found in the soil, plants and grains grown on contaminated soil,
and tissues of animals that eat contaminated plants and feed grains [1]. Because of
widespread environmental exposure, low levels of lead can be demonstrated in
tissues of clinically normal birds and animals [5] Lead toxicities occurs when an
animal or a bird inhales or ingests a concentrated source of lead. Concentrated lead
sources include lead-based paint, lead arsenate crop sprays, lead plates in automotive
batteries, fishing sinkers, lead shotgun pellets, drapery weights, sewage sludge, and
lead mine tailings [15].
Chickens are susceptible to lead intoxication. As little as 1.0 mg/kg lead in the
diet can cause significant depression in the growth of broiler chickens and consistent
reduction in blood d-aminolevulinic acid dehydratase, an erythrocyte enzyme
sensitive to lead.1 Clinical signs of acute lead poisoning in chickens include muscle
weakness, ataxia, and loss of appetite, followed by marked weight loss and eventual
cessation of egg production. A severe anemia may develop. Young chickens are more
susceptible than adult chickens [17, 20]. Long-term lead intoxication of chickens
results in degeneration of motor nerves in the spinal cord and loss of axons in
peripheral nerves without demyelination. In addition, muscles show atrophy and
degeneration of fibers.6 Attempts to measure the effects of lead on the chicken’s cellmediated immune response, humoral immune response, and interferon production
have yielded inconsistent results [24,28]. Lead ingested by chickens is deposited in
bones, soft tissues, and eggs and produces elevated blood lead levels.1 Bone lead
concentrations are by far the highest, followed by kidney and liver. The lowest
concentration of lead is found in skeletal muscle [24]. Eggs accumulate lead in their
shells, yolk, and albumen, with the highest concentration occurring in the shells.
MATERIALS AND METHODS
Lead concentration was extracted from the samples (muscle, liver, kidney,
spleen and heart) according to the method of.[14]. Samples were homogenized
separately and 5-10 g of the fresh homogenate were weighed into quartz dishes and
evaporated to dryness in an oven at 100° C (~16 h). Dried samples were ashed in a
muffle furnace at 450-500°C for 8-12 h. Ashed samples were cooled to room
temperature and 1.0 ml of concentrated nitric acid was added and the volume was
adjusted to 25 ml with deionized water. The metal was measured by atomic
absorption spectrophotometer (Perkin Elmer 5000). Lead was measured at
wavelength 217.0 nm with Hollow Cathode Lamp of lead. The limit of detection was
0.06 mg/kg for lead. The recovery of lead was studied by adding known amounts of
standard solution to different samples under investigation. The added amounts of lead
were selected so that they would be close to the amounts normally found in the
different samples. Recoveries in muscle, liver, kidney, spleen and heart ranged from
94-98%. All the results obtained were corrected according to the percentage of
recovery.
The material for analysis (fresh tissue from muscle, liver, kidney, spleen and
heart of three domestic animals – swine, sheep and goat) were taken from three
localities in the vicinity of the town Probishtip.
1. The first and second measuring point was the industrial zone in the town of
Probishtip – flotation of the lead-zinc ore.
2. The third measuring point was the locality in the vicinity of the waste landfill
near the village of Strmos.
3. The fourth measuring point was the control measuring point, located at 10 km
from the town of Probishtip where there are no sources of pollution with heavy
metals.
RESULTS AND DISCUSSION
Results presented in Tables (1-4) show the mean concentrations of lead,
cadmium, arsenic and Hg analyzed samples collected from heavy traffic, urban and
industrial areas from the different investigated chicken. The highest concentrations of
lead were detected in gaster, followed by liver samples.
Table 1: Concentrations of lead (Pb) in organs of chicken (mg·kg-1 fresh mass)
M.Point
Probishtip
1
Probishtip
2
Strmos
Control
Muscle1 Muscle2 Muscle3 Gaster
Cor
Liver
0,225
0,209
0,375
13,93
0,389
15,149
Plant
1
42,69
Plant
2
38,79
1,17
0,544
1,98
58,50
0,466
17,25
54,62
62,15
2,58
0,154
1,59
0,128
3,26
0,147
60,25
5,24
0,89
0,131
20,540
4,123
88,216
0,941
124,31
0,647
In respect of the measuring stations the highest values of lead content were
measured in Strmosh in whose immediate vicinity is the old tailings pond of the lead
and zinc mine “Zletovo”. The lead dust is carried by wind to greater distances and
contaminates the environment with heavy metals. The highest values are measured
in the stomach of chickens, 60.25 mg/mk fresh mass at the measuring place Strmosh
which is located near the landfill, while the value at the control point of measurement
that is considered relatively clean environment is 5.24 mg/kg. The plants that
chickens feed on are heavily contaminated with lead in Strmosh and the value is from
88.216-124.31 mg./kg dry mass. At other measuring points relatively low values of
lead content are measured (42.16-62.15 mg/kg dry mass in Probishtip), while at the
control measuring point the value is only 0.647 mg/kg.
Figure 1. Concentrations of lead (Pb) in organs of chicken (mg·kg -1 fresh mass)
The levels of lead varied according to the species of tissues and the locality
(Fig. 1 ).
Table 2: Concentrations of cadmium (Cd) in organs of chicken (mg·kg-1 fresh mass)
M,Point
Muscle1 Muscle2 Muscle3 Gaster Cor Liver Plant Plant
1
2
2,56
2,89
3,12
1,24
0,26
4,89
7,56
5,88
Probishtip
1
3,25
2,98
2,84
1,78
0,23
5,66
8,47
6,95
Probishtip
2
5,48
6,12
4,58
2,02
0,515 7,92
8,54
7,56
Strmos
0,05
0,12
0,09
0,496 0,026 0,54
1,24
0,98
Control
Table 2 gives the results for the content of cadmium in muscle tissue, stomach, heart,
liver and two types of plants that chickens were fed on. As for the measuring points,
the highest values are measured in Strmosh and in muscle tissue they vary from 4.58
to 6.12 mg/kg fresh mass. In internal organs the highest values are measured in liver
and they vary from 4.89 mg/kg (Probishtip 1) to 7.92 mg/kg (Strmosh). At the control
measurement point that is located outside any source of pollution with heavy metals
the lead content in liver is 0.54 mg/kg. The lowest values are measured in heart, from
0.026 mg/kg at the control measuring point to 0.515 mg/kg at the most polluted
measuring point (Strmosh).
Figure 2. Concentrations of cadmium (Cd) in organs of chicken (mg·kg-1 fresh mass)
Table 3: Concentrations of arsen (As) in organs of chicken (mg·kg-1 fresh mass)
M.Point
Probishtip
1
Probishtip
2
Strmos
Control
Muscle1 Muscle2 Muscle3 Gaster
Cor
Liver
0,118
0,092
0,089
2,57
0,010
0,056
Plant
1
21,58
Plant
2
29,54
0,124
0,115
0,098
3,152
0,014
0,076
24,58
31,59
0,154
0,026
0,126
0,012
0,113
0,016
5,842
0,458
0,017
0,008
0,098
0,005
36,59
2,54
45,51
3,24
Arsenic can get into the flesh by means of food that is contaminated with
pesticides, by treating animals with drugs that have arsenic and fattening them using
feed that contains arsenic. The meat should not have more arsenic than 1mg/kg, and
in organs 0,5 mg/kg.
The survey results show that relatively high values are measured in the
stomach (from 2.57 mg/kg in Probishtip 1 to 5.842 mg/kg in Strmosh) versus the
values obtained at the control point of measurement of 0.458 mg/kg. In plants that
chickens were fed on relatively high levels of arsenic were measured, from 29.5445.51 mg/kg dry mass of plants.
Figure 3. Concentrations of arsen (As) in organs of chicken (mg·kg-1 fresh mass)
Chart 3 clearly shows that in terms of the examined tissues of chickens highest
values are measured in liver at all measuring points, somewhat lower values in the
stomach, while muscle tissue contains the lowest values.
Table 4: Concentrations of mercury (Hg) in organs of chicken (mg·kg-1 fresh mass)
M,Point
Probishtip
1
Probishtip
2
Strmos
Control
Muscle1 Muscle2 Muscle3 Gaster
Cor
Liver
0,0025
0,0028
0,0014
0,009
Plant Plant
1
2
0,0025 0,0145 0,0358 0,0587
0,0031
0,0036
0,0023
0,010
0,0031 0,0159 0,0475 0,0662
0,0098
0,001
0,0087
0,001
0,0085
0,001
0,068
0,002
0,0078 0,0568 0,0845 0,0921
0,001 0,003 0,0012 0,0023
Mercury contamination of food chain can representa risk factor both for animal
and human health. For farm animals, European Commission Directive 2005/8/EC
permitted the maximum content of Hg 0.1 mg/kg of complete feedstuffs. Until now,
there have been no claims that Hg is an essential constituent of the diet for any
species (Underwood and Suttle, 1999).
Inorganic forms of Hg are poorly absorbed; the range was variously quoted 5–
15% of intake (Clarkson, 1987) and 1–3% (Kostial et al., 1978), but in very young
animals 30–40% of intake (Kostial et al., 1978). Methylmercury is a more available
form of Hg (Underwood and Suttle, 1999). Houserova et al. (2005) found the highest
mercury concentration (39.2 mg/kg dry matter) in liver of an adult population of
cormorant (Phalacrocorax carbo) while the content of mercury in younger
individuals it was approximately six-times lower (5.8 mg/kg DM). Srebocan et al.
(2007) mentioned that with the increasing age the concentration of Hg in the
organism of bluefin tuna (Thunnus thynnus) increased as well. Goutner et al. (2001)
did not find significant correlation of mercury levels in feathers of squacco heron
(Ardeola ralloides) with age. We did not find any literature data on Hg accumulation
in chickens.
The objective of this research was to determine the differences in toxic
dynamics of mercury in the body of chickens with different measuring point.
The results obtained indicate relatively low levels of mercury content in the
examined tissues at all measuring points compared to the control point of
measurement.
Influence of age on the retention of total Hg was investigated in laying- and
meat-type chickens. To evaluate the effect of age as exactly as possible, it is
necessary to carry out a great number of estimations within very short time intervals
during a longer period of life.
Figure 4. Concentrations of mercury (Hg) in organs of chicken (mg·kg -1 fresh mass)
CONCLUSION
1. The results of research on the content of lead, cadmium, arsenic and mercury in
muscle 1, muscle 2, muscle 3, liver, and cor, gaster, show a variation of values
in a relatively wide range between respective measurement sites. In terms of
research, the highest values were obtained in the stomach and liver, and lowest
values were measured in heart tissue.
2. Relatively high values of all tested elements - lead, cadmium, mercury and
arsenic were measured in muscle tissue of chickens in Probistip and Strmosh
areas. Muscle tissue is most consumed (chicken meat) by man and therefore
should not be used in the diet. All this is very harmful to human health and can
have serious consequences upon future generations.
3. These significantly high concentrations of lead in the stomach and liver in the
industrial zone of Probishtip and the vicinity of the village Strmosh suggest that
an appeal to the population should be made to avoid the consumption of these
organs.
4. At the control point of measuring the lead content in all examined tissues from
the organs of chickens is significantly low compared to the industrial zone of
Probishtip and the vicinity of the village Strmosh.
5. All the above mentioned facts require greater commitment to remediate the
harmful effects of heavy metals on the environment and man.
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